The present invention relates generally to data entry using a digitizer device and, more particularly, to a system and method for identifying forms placed on a digitizer and for determining and correcting digital image offset for digitizer pads.
Systems are known that automatically identify forms placed on a digitizer device. (The term xe2x80x9cform,xe2x80x9d as used herein, refers to a printed image on a page, rather than to an actual page; that is, if two pages are printed with the same image, they are considered the same form.) For example, U.S. Pat. No. 5,869,789 (Reid-Green) discusses a page recognition system that detects a page number pre-coded onto a sheet of paper when the sheet of paper is mounted on the digitizer system. The system utilizes a built-in scanner to detect a pre-coded page identifier on the back-side of the page. U.S. Pat. No. 5,555,101 (Larson et al.) discusses an automated page recognition system for forms received by facsimile and also uses a pre-printed pattern to identify a form.
U.S. Pat. No. 5,629,499 (Flickinger et al.) discloses an electronic clipboard and discusses two methods for recognizing forms used thereon. In the first method, a toggle switch is used to toggle between various form identifiers displayed on the clipboard; in the second method, a bar-code reader reads a bar-code pre-printed on the form. The toggle-display requires the clipboard to contain a micro-processor that may need to be re-programmed every time a new set of forms is used.
Digitizing notepads are known that record notations made on paper forms mounted thereon. For example, A.T. Cross Company has marketed a CrossPad 35 (see FIG. 1), a portable digital notepad that digitizes and records pen movements using radio transmission. The CrossPad transmits the recorded pen movements to a personal computer for processing and analysis. The CrossPad, however, is not itself capable of identifying pre-printed forms. The information recorded by the CrossPad and transmitted to a computer only comprises the pen strokes entered by a user writing on a form. Information pre-printed on the form cannot be detected by the Crosspad. The CrossPad does not have a form ID display that can be toggled through by a user, nor does it have a bar-code reader.
Because devices such as the CrossPad only detect information that is written by a user, such devices generally cannot be used in systems that identify a form based on pre-printed information. Even systems such as those disclosed in Reid-Green are not capable of detecting form identification information when multiple forms are placed on the digitizer. For example, Reid-Green would only identify the form that is at the bottom of the stack. The device discussed in Flickinger et al. might be capable of reading multiple pages, but such a device requires additional (and costly) form-reading mechanisms not present in CrossPad-type devices. The use of a bar-code reader or other form-reading mechanism in a digitizer increases the cost and the weight of the digitizer.
Another drawback of CrossPad-type devices is that the spatial relationship of written marks on the paper form is not identical to the spatial relationship of the corresponding digital markings on the underlying xe2x80x9cdigital form.xe2x80x9d This offset (xe2x80x9cdigital driftxe2x80x9d) can be as much as several millimeters.
A further drawback of CrossPad-type devices arises from the fact that when a form is used, the pre-printed information on the form is not part of the digital ink file that is uploaded. In order for the digital ink file to be optimally useful after upload, an image of the contextual information present on the paper form at the time of use needs to be added to the digital ink image. The two images must be correctly aligned, so that an image of the original form, with the information written thereon, can be re-created.
There is therefore a need for a system of automated form identification that is capable of recognizing forms used on the CrossPad, and similar devices, without relying on pre-printed information on the forms.
There is a further need for a system that does not require a cumbersome LCD display (along with a programmable microprocessor) and toggle switch or other input device to be integrated into a CrossPad-type of electronic clipboard.
There is a further need for a method and system for correcting digital drift for CrossPad-type devices and other digitizers. There is a further need for a method of combining and aligning a digital ink image of handwritten information on a form with an image of the underlying form.
The present invention comprises a method for automated identification of pre-printed forms, comprising the steps of identifying the existence and location of a mark made manually on a pre-printed form and identifying the pre-printed form by comparing the location of the mark to a database listing forms and corresponding locations of identifying marks. The invention further comprises a system for identification of pre-printed forms, comprising a digitizer; a pre-printed form comprising one or more pre-printed indicators unique to the form indicating where a user is to enter one or more identifying marks; and a computer processor, coupled with a database, that receives one or more digitized images of marks made on the form, identifies the existence and location of one or more identifying marks made by the user, and identifies the form by comparing the location of said one or more marks to a database listing forms and corresponding locations of identifying marks. The present invention also comprises computer software for automated identification of pre-printed forms, comprising software for receiving and storing data describing the location of a mark made manually on a pre-printed form and software for identifying said form by comparing the location of said mark to a database listing forms and corresponding locations of identifying marks.
The present invention further comprises a method for correcting digital drift and for mapping a digital ink file onto a digital form. Typically, a digitizing pad (e.g., a CrossPad or similar device) suffers from a certain amount of digital driftxe2x80x94the spatial difference between the relative location of a writing on a paper form and the relative position of the corresponding digital mark on the underlying digital form. The amount and direction of digital drift is constant for each pad (and anywhere on a given form), but typically varies from pad to pad.
Software of a preferred embodiment determines the amount and direction of digital drift by reference to a known landmark on a given form. Preferably, such a landmark is a form-identification mark, discussed below. In a preferred embodiment, the form identifier is a circle. The digital drift is determined by comparing the known position of the center of the form identifier circle on the paper form with the center of the corresponding digital mark on the digital form underneath, then determining variances in horizontal and vertical directions. Once the digital drift is determined, it is applied as a correction factor to all of the digital markings on the form.
This correction factor is preferably used to facilitate the alignment of a handwritten digital ink image with an image of the underlying form. This alignment is accomplished by first identifying the form that digital ink data was written on. A pre-loaded image of the identified form is then retrieved from a database. The correction factor is used to align the ink data with the digital form. The correct alignment of the digital form with the digital ink enables replication of the paper form as it appeared when it was filled out. The correct alignment further enables the composite image to be processed by optical mark recognition (OMR), optical character recognition (OCR), and image snippets storage into a database.
The present invention further comprises a method and system for creating enabling identification of forms that have not had a form-identification mark pre-printed thereon. In a preferred embodiment of this aspect of the invention, a metal or plastic guide with three-millimeter holes positioned at various selected locations in the guide is affixed to one side of a digitizer pad. Preferably, the guide is affixed at a pre-determined location linked to a customer. The fixing of the guide to the side of the pad in a pre-determined location enables a user to make a mark in a hole, wherein the location of the hole corresponds to the location that a pre-printed mark would have. That is, the mark has the same location that a mark that filled in a pre-printed form identification circle would have. This allows clients who have preprinted forms that were not printed with form identification marks to use those forms in the remainder of the disclosed system.